Sectioners

ABSTRACT

A machine for sectioning and measuring thin layered materials such as are used in semiconductors in which: the workpiece is positioned in a mechanical chuck which supports and protects the workpiece during the operations of sectioning, cleaning, staining, transfer and measurement, the machine includes electromagnetic elements for biasing the workpiece into engagement with a rotary abrasive tool of precisely known radius and the force of the electromagnet is manually adjusted by a rheostat having a pointer dial and an index of section width marks so referenced to the dial and the rheostat that setting the pointer dial to any width mark of the index results in application of the correct bias force of the workpiece toward the rotary tool for the section width to which the dial is set. Contamination of the work area by spent coolant is prevented by applying the coolant to the rotary abrasive tool at a controlled rate by a positive displacement pump, spreading it evenly over the surface of the tool and removing it with a resilient blade before it exceeds a film thickness at which adhesive and cohesive forces are greater than the centrifugal forces acting upon it. Damage to work pieces is prevented by an automatic time delay relay which delays the application of the selected bias force for several seconds after the start of each sectioning operation.

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Turner States Patent [1 1 [451 July17,1973

[ SECTIONERS [76] Inventor: Roger Scott Turner, 620 Carpent Lane, Philadelphia, Pa. 191 19 221 Filed: Mar. 30, 1971 211 App]. No.: 129,464

UNITED STATES PATENTS 1,601,339 9/1926- Ballou 51/98.5 2,342,146 2/1944 Joyce 51/217L X 1,936,016 11/1933 Hay 51/218 F X 2,817,193 12/1957 Unzicker 51/217 R Primary Examiner-Donald G. Kelly [57] ABSTRACT A machine for sectioning and measuring thin layered materials such as are used in semiconductors in which:

the workpiece is positioned in a mechanical chuck which supports and protects the workpiece during the operations of sectioning, cleaning, staining, transfer and measurement, the machine includes electromagnetic elements for biasing the workpiece into engagement with a rotary abrasive tool of precisely known radius and the force of the electromagnet is manually adjusted by a rheostat having a pointer dial and an index of section width marks so referenced to the dial and the rheostat that setting the pointer dial to any width mark of the index results in application of the correct bias force of the workpiece toward the rotary tool for the section width to which the dial is set. Contamination of the work area by spent coolant is prevented by applying the coolant to the rotary abrasive tool at a controlled rate by a positive displacement pump, spreading it evenly over the surface of the tool and removing it with a resilient blade before it exceeds a film thickness at which adhesive and cohesive forces are greater than the centrifugal forces acting upon it. Damage to work pieces is prevented by an automatic time delay relay which delays the application of the selected bias force for several seconds after the start of each sectioning operation.

13 Claims, 15 Drawing Figures PATENIEU JUL 1 7197s SHEE! 3 BF 4 INVENTOR SECTIONERS This invention relates to the measurement of the thickness and uniformity of layers of solid materials and particularly thin layers of solid state materials used in devices such as semi-conductors wherein the control of layer thickness is essential to their function.

As the semi-conductor industry has developed ever more complicated and miniaturized devices, the problem of measurement and control of the thickness and uniformity of each of the layers of materials used in such devices has become increasingly critical. At the same time, production of these devices has become hypersensitive to contamination by various materials so that many of the steps of manufacture must be performed under ultra clean conditions in so called clean rooms.

The machine of the present invention produces grooves of known radius, precisely measurable width and exceedingly fine finish through layers of the various materials used in semi-conductor devices so that the thickness of the layers can be accurately determined by reference to an index which shows the depth corresponding to any width measurement of grooves produced by the machine. Such an index has been developed by computer for use in conjunction with the machine of the present invention. The index is based on the use of rotary abrasive tools having a radius of exactly 0.75 inches. The width measurements of theindex are at intervals of 0.0001 inch over the useful working span of groove widths for which the machine is designed. Each layer of material has a thickness which is equal to the difference between the depth of the groove as measured from the top surface of the layer and the depth of the groove as measured from the bottom surface of the layer. The width of the groove at the top and at the bottom of each layer is clearly defined and readily measured by optical microscopy when the machined surfaces of the layers are smooth and properly stained.

Prior to the present invention the methods generally used for sectioning and measurement of the layers of semiconductor devices entailed laborious messy operations and required specially trained technicians working at a safe separation from the clean room manufacturing operations.

A primary object of the present invention is to improve the ease, convenience and speed with which thin layers or films of material may be sectioned and measured.

Another object of the present invention is to improve the precision and reliability of measurement of thin layers of material.

A further object of the present invention is to eliminate the messiness and risks of process contamination associated with wet lapping operations of sectioning and to make practical the performance of sectioning operations in clean rooms.

Still another object of this invention is to reduce the number of steps required in the sectioning and precision measurement of layers of solid state material.

Yet a further object is to provide mechanical shielding as an integral part of a work piece holding device so that fragile thin flat work pieces may be inserted into the holding device, positioned, examined, sectioned, cleaned, dried, stained and otherwise processed, han

dled and removed with a minimum risk of loss or damage of such work pieces.

Still another object of the present invention is to provide a device for holding thin flat work pieces for processing which is simple rugged and durable in the presence of water, solvents and a wide variety of dyes and chemical reagents.

These and other objects will be apparent from an examination of the following drawings and specifications in which:

FIG. I is a front elevation of the overall machine of the present invention with its rotary tool and its work piece holding chuck in place with the chuck in its retracted position and with the dials set to their non operating positions.

FIG. 2 is a side elevation of the overall machine as viewed from the left side of FIG. 1 but with its chuck removed and with its housing partly cut away to show its rheostat and the location of other electrical components.

FIG. 3 is a side elevation taken from the opposite side from FIG. 2 and with the housing partly cut away to show the coolant supply system and the timer.

FIG. 4 is a side elevation of the mechanism of the machine partly sectioned to show details.

FIG. 5 is a cross sectional view taken along line 5-5 of FIG. 4 as viewed from the rear of the machine showing details of the drive mechanism.

FIG. 6 is a longitudinal cross sectional view of the ro-.

tary abrasive tool of the machine showing how it is mounted to the spindle of the machine.

FIG. 7 is a fragmentary cross sectional view taken along line 7-7 of FIG. 4 as viewed from the left of FIG. 4 showing the means for adjusting the alignment of the chuck in the machine.

FIG. 8 is an enlarged front elevation of the center part of the machine partially sectioned to show certain details of the force control magnet and of the chuck and means for support of the chuck in the machine in its operating position.

FIG. 9 is an enlarged partially cross sectioned view of the coolant pump of the machine as viewed in FIG. 3 showing details of its mounting and adjustment.

FIG. 10 is an enlarged exploded cross sectional view taken along lines 10-10 of FIG. 3 showing the coolant passage in the coolant distributor of the machine.

FIG. 11 is an enlarged fragmentary front view of the coolant distributor partially sectioned to show the flow control parts in detail in. their open position and the blade of the distributor in its retracted position.

FIG. 12 is an enlarged fragmentary front view of the coolant distributor partially sectioned to show the flow control parts in detail in their closed position and the distributor blade in its operative position.

FIG. 13 is a perspective view of the work piece holding chuck of the machine of the present invention in its open position and with a typical large work piece in place in the chuck.

FIG. 14 is a crosssectional view taken along line 14-14 of FIG. 13 showing the manner in which very 7 small work pieces may be supported in the chuck of the plate, a mechanism housing 14, a spindle supported in headstock 16, by a pair of widely spaced spindle bearings 17 and driven by motor 12, through pulleys 18 and 19 and belt 20. Pulley 18 is secured to motor shaft 21 by set screw 22 and pulley 19 is secured to spindle 15 by set screw 23. Headstock 16 is secured to baseplate 11 by screws 24. The axis of spindle 15 is parallel with base plate 11. Worm gear 9 is secured to spindle 15 by set screws 10.

A rotary abrasive tool 13 is held on a common axis with spindle 15 by tapered sleeves 25 between collar 26 which is secured to spindle 15 by set screw 27 and collar 28 which is secured by thumb screw 29. A shaft 30 is supported in headstock 16 parallel to spindle 15 by a pair of widely spaced bearings 31 which are pressed into headstock 16 and preferably made of self lubricating material such as graphited bronze. Arm 32 is secured to shaft 30 by screw 33 and has a control knob 34 secured to its upper end by a threaded stud 35.

With further reference to FIGS. 3,4, and 5, one end of shaft 30 passes through a clearance hole in the lower end of yoke 36 and is prevented from axial movement with reference to yoke 36 by collars 37 which are secured to shaft 30 by set screws 38. The upper end of yoke 36 closely straddles eccentric 39 which is an integral part of worm wheel 40 which is preferably molded a pair of raised flat work-piece support surfaces 59 are in a common plane along the opposite longitudinal edges of opening 58 on the inner side 60 of web 57.

of a self lubricating resin compound. Worm wheel 40 rotates on one end of hardened pin 41, the other end of which is pressed into support 42. Support 42 is pressed into a boss 43 of headstock 16 as is also hardened pin 44. Support 42 and pin 44 are parallel to spindle 15 and are spaced apart by the overall width of worm wheel 40 plus working clearance. The thickness of the upper end of yoke 36 is the same as that of eccentric 39.

With reference to FIGS. 3,4,5, and 9 support 45 is pressed into boss 46 of headstock l6 and is parallel to support 42. Two tapered apertures 47 in support 45 contain the upper ends of pump tube 48 which is made of thin resilient high tensile strength synthetic rubber. Three rollers 49, preferably made of self lubricating material such as graphite-bronze are secured to worm wheel 40 by hardened steel pins which are pressed into it at equal distances from its center and 120 apart. Tube 48 is stretched over rollers 49 so that rotation of worm wheel 40 results in a flow of the contents of tube 48 in the direction of rotation of worm wheel 40 as indicated in FIG. 4. Eccentric 39 has its center only slightly offset from the center of worm wheel 40 and produces a short reciprocation of yoke 36, shaft 30 and arm 32.

Refering to FIGS. 4 and 8, magnet arm 50 is secured at one end to shaft 30 by set screw 51 and has integral magnet armature 52 at its opposite end. Electromagnet 53 is secured to headstock 16 by screws 54. Electromagnet 53 when energized by an electric current, pulls downward on armature 52 and thus exerts a force on arm 50,shaft 30 and arm 32 which tends to rotate them clockwise about the axis of shaft 30 as viewed in FIG. 8.

Referring to FIGS. 1, 8,13 and 14, chuck 54 is an-important part of the machine of the present invention" and contributes importantly to the accuracy, speed, convenience and safety of its operation. Main jaw 55 of chuck 54 is channel shaped in section and has parallel side rails 56 and a web 57. An elongated opening 58 extends between and at right angles to side rails 56 and Web 57 is notched to provide a recessed latch keeper 61 so that when chuck 54 in its closed condition as shown in FIG. 8 no part of latch 62 extends beyond the upper end 63 ofjaw 55. Outer side 64 ofjaw 55 is flat and parallel with surfaces 59 over most of its area. A step 67 increases the thickness at one end of web 57 and side rails 56 thus rigidifying web 57 and providing sufficient section width for V shaped mounting notches 68 which have their centers close to and on a line running parallel with the plane of surfaces 59. Outer side 64 ofjaw 55 is concave in section adjacent to the longitudinal edges of opening 58. The radius of curvature of concave section 69 is larger than the radius of tool 13 to provide running clearance. Set screws 70 located at both sides of the lower ends ofjaw 55 as shown in FIG. 7 provide means for critical alignment of the chuck with reference to the surface of tool 13.

Refering to FIGS. 8 and 13 hinged jaw 71 is pivotally secured to main jaw 55 by pointed set screws 72 which have a common center line running parallel to surfaces 59 and to the longitudinal center line of opening 58. Set screws 72 are threaded into side rails 56 and their pointed ends enter shallow tapered indentations in the sides of hinged jaw 71. Latch 62 is pivotally secured to jaw 71 by flat head screw 73 which is threaded into recessed web 74. Warped spring washer 75 has an inner diameter much larger than the shank of screw 73 and maintains itself in a position from which its force against latch 62 results in a clockwise bias of latch 62. When jaw 71 is closed,latch 62 retains it in a position in which its inner surface 76 lies parallel to surfaces 59. A pair of grooves 77, separated by a distance equal to the width of opening 58, run parallel with and equidistant from the longitudinal centerline of opening 58. Resilient material such as rubber tubing 78 is tightly packed into grooves 77, leaving tubing 78 protruding as shown.

Preferably a cover strip 79 of acid resistant resilient material such as Teflon tape is applied over the pr0trusions to protect the rubber from strong acids used in stains which may be applied to work pieces while they are held in the chuck. All other parts of the chuck are also made of acid resistant material. .law 71 is preferably made of clear transparent polycarbonate and metal parts are preferably made of stainless steel. When latched closed, all parts of hinged jaw 71 lie within the channel section of jaw 55 as shown. The tops of side rails 56 and the bottom of step 67 as viewed in FIG. 13 are flat and parallel with surfaces 59. A set screw 80 is set to protrude downward from web 57 exactly the same distance as does step 67. Both ends of main jaw 55 are perpendicular to its sides. Set screw extends from support arm 32 to selectively engage any of a series of identical grooves 81 on the outer side ofjaw 71. The chuck is opened for removal of the workpiece by pressing latch release lever 134.

The transparency of jaw 71 and the translucence of Teflon cover strip 79 enable the user to see whether the workpiece is in position to be properly clamped by the jaws of the chuck even when the jaws are latched in their closed position.

In FIG. 13 a large work piece 82 is shown supported on work piece support surfaces 59 where it can be positioned as required to expose the part to be sectioned.

In FIG. 8 work piece 82 is shown being held between support surfaces 59 and cover strip 79 by rubber tubing 78.

It is sometimes necessary to section work pieces which are too small to be directly supported in the above manner. As shown in FIGS. 13 and 14 the width of opening 58 may be increased for a portion of its length as at section 14 14 to enable a small work piece 83 cemented to a microscope cover glass 84 to be supported in the chuck with any selected part of work piece 83 centered in opening 58 for sectioning.

The chuck may be made without the enlargement of opening 58 in order to increase its capacity for large work pieces or the chuck may be made narrower than shown in the drawings for holding only small work pieces.

Refering to FIGS. 1 and 8 arm 32 may at any time be moved manually between its retracted position as in FIG. 1, which allows emplacement or removal of chuck 54, and its engaged position as in FIG. 8.

Arms 50 and 32 are positioned on shaft 30 so that when chuck 54, holding a work piece 82 is in place in the machine and in its engaged position as in FIG. 8 the gap between magnet pole piece 85 and armature 52 is only a few thousandths of an inch. Precise adjustment of the distance between pole piece ends 85 and armature 52 is normally made only once by set screw 90. A projection 86 of armature 52 is proportioned to slightly enter between pole piece ends 85. This provides a much extended range of adjustment of the distance be tween armature 52 and pole piece ends 85 over which the torque developed by the magnet is within satisfactory limits. Pole piece separator 87 and magnet mounting shim 88 are made of non magnetic material.

Refering to FIGS. 3,4,5,8,9,10,11 & 12 a coolant system is included which comprises water supply pan 89, supply line 91, pump 92, delivery line 93 and means for controlling, distributing and filtering the coolant as hereinafter described.

Coolant is drawn from coolant pan 89 through supply line 91 to pump 92 through which it is pumped by the action of rollers 94 rolling over stretched tube 95 in the direction indicated in FIG. 4. Coolant is delivered by line 93 to coolant distributor 96.

Refering to FIG. 10, coolant enters distributor 96 through nipple 97 and passage 98 in shaft 99 from which it flows through an aperture 100 in resilient blade 101 and then upward through groove 102 of trough 103.

Refering to FIGS. 2,4,1] and 12 resilient blade 101 is preferably made of thin resilient water resistant material such as polyester and is secured in place on shaft 99 by trough 103 and screws 104 which are threaded into shaft 99. Shaft 99 is parallel to spindle and is rotatably mounted in boss 105 of headstock 16. Axial movement of shaft 99 is prevented by collars 106 and 107 which are secured by set screws 108.

Refering to FIGS. 8, 11 and 12, set screw 109 is threaded into the side of headstock l6 and cooperates with sliding pin 110 and cam 111 of shaft 99 to control the flow of coolant through line 93. In FIG. 11, lever 112 which is threaded into collar 107 is shown in position for a sectioning operation. In this position of lever 112, blade 101 contacts tool 13 and line 93 which is made of rubber is closed by cam 11] to prevent the flow of coolant. Rotational movement between the above mentioned two positions of lever 112 is limited by stop pins 113 which are pressed into headstock 16.

Refering to FIGS. 3, 4, 8 and 10, coolant flowing from groove 102 during a sectioning operation contacts tool 13 which rotates counterclockwise as viewed in FIG. 8 and quickly spreads evenly along the full length of tool 13. I have found that by supplying the coolant at a uniform low rate, spreading it evenly, controlling the drip-off and limiting the speed of the 1% inch diamter tool to 750 revolutions per minute, no coolant is thrown or splashed at any stage of a sectioning operation even when plain water is used as the coolant. Trough 103, which is slanted downward to the right as viewed in FIG. 3, collects all excess coolant and returns it to pan 89. Returning coolant drips onto filter paper 125 retained in pan 89 by perforated tray 126.

Refering again to FIGS. 1, 2, 3 and 8, an electrical interval timer 114 of conventional design is mounted on housing 14 and is controlled by pointing dial 115 and start button 116. Time index numbers in minutes are marked on housing 14 as illustrated. A rheostat 117, also of conventional design, is mounted on housing 14 and is controlled by pointer dial 118. Force index numbers, corresponding to the widths of work pieces are marked on housing as illustrated.

The complete electrical circuit of the machine is shown diagramatically in FIG. 15 and includes electric supply plug 119, fuse 120, timer 114, time delay relay 121, rectifier 122, magnet 53, motor 12, capacitor 123 and rheostat 117. The time delay relay, electrical terminals, fuse, capacitor and rectifier are all mounted together on a single board mounted to base plate 11 and located at the rear of the machine as represented generally by electrical section 124 of FIG. 2. The moving contact 127 of time delay relay 121 is illustrated in its delay" position in which current passes from contact 127 to stationary contact 128 and resistor 129. Contact 127 is shown in phantom in its normal position in which current passes from contact 127 to stationary contact 130 so that resistor 129 is eliminated from the circuit.

Resistor 131 may be used for reducing the strength of magnet 53 at all positions of rheostat 117 and is optional. At the position of rheostat 117 corresponding to zero force, the strength of the magnet only counterbalances the weight of chuck 54.

To prepare the machine for operation, the supply cord plug 119 is connected to a -120V AC outlet, the water pan 89 is filled about two thirds full of coolant, arm 32 is set to its retracted position, as shown in FIG. 1, and a rotary abrasive tool 13 is secured on spindle 15, between tapered bushings 25, by means of thumb screw 29 and collar 28. Coolant control lever 112 is then moved counter-clockwise to stop 113, time control dial is set at the 2 minute position and starter button 116 is pressed to.start the machine and run it sufficiently to prime the coolant system. Priming.

is not subsequently needed, unless the coolant system is drained.

To perform a sectioning operation, the work piece 82 is placed in chuck 541 as shown in FIG. 13 and positioned so that the area to be sectioned is along the longitudinal center line of opening 58 and secured there by latching hinged jaw 71 in its closed position. Arm 32 is then set in its retracted position, as shown in FIG. 1, so there is sufficient clearance between arm 32 and tool 13 to easily place chuck 54 in operating position on shaft 30. Arm 32 is prevented from excessive rotation in a counter-clockwise direction, as viewed in FIG. 1, by armature 52 contacting shaft 25. Chuck 54 is then positioned along shaft 30 with the closest one of the grooves 81 to the center of the work piece engaged with set screw 90. This is easily done, due to the transparency of jaw 71 and the translucence of tape strip 79. Arm 32 is then moved clockwise to cause work piece 82 to contact tool 13. The duration time of a sectioning operation is selected by turning time pointer dial 115, so that it indicates the selected operating time duration. The abrading force is selected by turning force dial 118 so that it indicates the width of the work piece, where it is to be sectioned, to the closest V4 inch. As progressively wider settings are selected, the rheostat is consequently set to lower resistance values, so that the magnetic force and the resultant abrading force are correctly adjusted in accordance with section width.

Start button 1 16 is then pressed to start the machine. Pressing button 116 closes contacts 132 and 133 of timer 114, to close circuits through timer 114, resistor 131, time delay relay 121, resistor 129, rectifier 122, magnet 53, rheostat 117 and motor 12. Contacts 132 and 133 are kept closed by timer 114 until the selected operating time has elapsed, when they are again opened.

The effect of time delay relay 121 is to initially energize magnet 53 at reduced current, at any selected position of dial 118, in order to allow time for the coolant to thoroughly wet rotary tool 13 and to allow rotary tool 13 to become seated against the work piece. After a delay of a fraction of a minute, during which the tool and work piece have been well wetted with coolant, time delay relay 121 switches contact 127 from contact 128 to contact 130 to eliminate resistor 129 from the circuit and energize the magnet at normal force, according to the setting of rheostat 117, for the remainder of the sectioning operation.

When the machine is stopped by timer 114, arm 32 is moved manually to its retracted position and chuck 54 is removed from the machine. The work piece is left in place in the chuck, for cleaning of the section and optical measurement of the sectioned layer or layers, either by microscopy or interferometry. Staining of one or more layers of sectioned material is often required, in order to obtain sufficient optical definition and the staining operation is also performed in the chuck by wiping the section with a stain soaked swab and then rinsing with water and drying with a'blast of compressed air or gas. The work piece is usually quite fragile and often represents considerable manufacturing cost before it is sectioned. Therefore, its protection in the chuck during all stages of sectioning, handling, cleaning, staining and measurement, is important in speeding production and preventing breakage.

It is sometimes necessary to perform the sectioning operation at a very precisely located and oriented part of the workpiece. The sides and ends of the chuck of the present invention facilitate the instant location of the chuck, on the stage of a microscope, by means of a simple right angle fence, aligned and attached to the stage, in conventional manner.

When the surface of a workpiece is scanned in a microscope, in order to locate the part to be sectioned or in order to examine or measure a sectioned layer for uniformity of thickness, it is important to have the surface being examined remain in focus as it is moved across the field of vision of the lense. This is accomplished by the machine and method of this invention, whether the optical work is performed with the chuck resting on an instrument stage, with the opening of the chuck facing upward toward a downward aiming lensc, or facing downward toward an upward aiming lensc, because: 1. The supporting surfaces of the chuck are in both cases parallel with the work piece support surface of the chuck. 2. The work piece is supported in the chuck from the same side of the work piece on which the section is performed. 3. The sectioning machine is capable of producing sections of uniform depth and cross section throughout the length of the sections.

Very small work pieces are examined and measured with little or no scanning, so it is not necessary to support them in the chuck from the same side which is sectioned.

Thus it will be seen that the chuck of the machine of the present invention serves importantly at each stage of the process.

Because of the precise location of the chuck in the machine and the fact that the work piece is left in the chuck during all of the other stages of processing, handling and measurement, a work piece may be returned to the machine, after it has been sectioned and examined or measured, for further sectioning in the same exact area.

Determination of the thickness of a sectioned layer may be made either by counting the number of interference bands of monochromatic light of known wavelength across a sectioned layer by means of an interferometer or by measuring the width of the sectioned layer at its top and at its bottom surfaces and translating the two width measurements into corresponding section depth dimensions so that the layer thickness can be determined as the difference between the two depth dimensions. The latter method is usually preferable because it is capable of even higher precision than the interferometry method.

In order to simplify and speed the procedure for converting section width measurements into depth dimensions and to achieve high precision with minimum risk of computational error, a special conversion chart has been developed for sections of 0.75 inch radius. The chart consists of paired columns of numbers in which the numbers of the first column are section width dimensions to the closest 0.0001 inch by 0.0001 inch increments and in which each width dimension of the first column has the precise section depth dimension of a section of that width directly to its right in the second column.

For example: A section having a width of 0.0397 inch as measured at the top surface of a layer has a depth dimension from the top of the layer to the bottom of the section of 0.000264. The same section has a width of 0.0332 inch as measured at the bottom surface of the same layer and has a depth dimension from the bottom of the layer to the bottom of the section of 0.000185 inch. The difference between the two depth measurements is 0.000081 inch which is the precise thickness of the layer. 7

Section Width Section Depth 0.0332 0.000l84 0.0333 0.000185 0.0334 0.000187 Thus it will be seen that the sectioning machine of the present invention, when used in accordance with the process of the present invention fully achieves all of the objectives stated herein.

It will be understood that the present invention is capable of various modifications and embodiments other than those illustrated without departing from the scope of its teaching.

I claim:

1. In a machine for sectioning thin flat solid materials, a rotary abrasive tool mounted in said machine for rotation about a fixed axis, motor drive means for rotating said tool, a chuck for adjustably positioning and holding thin flat work pieces in contact with said tool for sectioning selected flat areas of said work pieces and a chuck rest for supporting and aligning said chuck in said machine, said chuck including a first jaw having a rigid flat surfaced work piece support, an opening in said support for entry of said rotary tool into engagement with said work piece, a second jaw having surfaces for pressing work pieces into contact with said support closely adjacent to both of a pair of opposite edges of said openings so that said work pieces will be supported closely adjacent to both sides of said selected flat areas of said work pieces, said jaws being pivotally interconnected for pivoting between an open position for receiving, positioning, and removing work pieces and a closed position for holding and protecting work pieces, jaw holding means for holding said jaws in said closed position, manual release means for releasing said jaw holding means and bearing surfaces on said chuck for cooperating with said chuck rest to support said chuck and rigidly align said work piece support with the axis of rotation of said rotary tool.

2. A machine in accordance with claim 1, in which said chuck rest comprises a shaft mounted in said machine with the axis of said shaft parallel with the axis of said rotary tool and in which said bearing surfaces comprise a pair of V shaped notches spaced apart in the lower end of said chuck.

3. A machine in accordance with claim 1, in which said jaw holding means comprises a mechanical latch and a latch keeper and in which all parts of said latch and said latch keeper are recessed into the jaws of said chuck.-

4. A machine in accordance with claim 1 in which said second jaw includes resilient material located closely adjacent to said pair of opposite edges when said jaws are closed (for pressing work pieces into firm contact with said support) so that said work pieces will be pressed into contact with said support only in areas closely adjacent to said edges of said opening.

5. A machine in accordance with claim 1 in which said first jaw is channel shaped in cross section and includes an interior surface and an external surface (an elongated opening passing) and in which said opening is elongated and passes from said interior surface to said exterior surface, with the longitudinal center line of said opening parallel with the axis of rotation of said rotary tool and in which said exterior surface is concave in cross section adjacent to the longitudinal sides of said opening to permit part of said rotary tool to protrude through said opening to perform a sectioning operation on a work piece held in said chuck.

6. A machine in accordance with claim 5, in which said interior surface is embossed along the longitudinal edges of said opening so that flat work pieces will be contacted closely adjacent to said opening even when said work pieces have slightly irregular surfaces or when particles of material are present on other areas of said interior surface.

7. A machine in accordance with claim 4, in which at least that part of said resilient material which contacts said work pieces is resistant to wetting and non adhesive to metals and in which said work piece support is easily wettable so that the presence of moisture between said work pieces and said work piece support will retain said work pieces in position on said support when said jaws are in said open position and when said jaws are moved from said closed position to said open position.

8. A machine in accordance with claim 1, in which at least two of said bearing surfaces are adjustable by means of set screws mounted in said first jaw.

9. A machine in accordance with claim I, in which at least part of said second jaw is translucent.

10. A machine in accordance with claim 1, in which at least part of said first jaw is channel shaped in cross section and said second jaw lies within said part of said first jaw when said jaws are in said closed position.

11. In a machine for sectioning thin flat easily frangible solid materials such as germanium arsenide or silicon as used for substrates in the semi-conductor indus try, a rotary abrasive tool mounted in said machine for rotation about a fixed axis, motor drive means for rotating said tool, a chuck for holding selected areas of said work pieces in contact with said tool and a chuck rest for supporting and aligning said chuck in said machine, said chuck including a pair of hinged jaws having an open position for receiving, positioning, and removing work pieces and a closed position for holding and protecting work pieces, said work pieces being substantially completely covered on both sides by said jaws except for said selected areas of said work pieces when said jaws are in said closed position.

12. In a machine for producing grooves which have precisely known and uniform section radius to enable the measurement of thickness of thin layers of solid materials by a procedure which includes optical measurement of the groove width at the top and at the bottom of each layer to be measured, a rotary abrasive tool mounted in said machine for rotation about a fixed axis, motor drive means for rotating said tool, a chuck for holding selected areas of work pieces in contact with said tool for sectioning said selected areas and a chuck rest for supporting and aligning said chuck in said machine, said chuck including a first jaw having a rigid flat surfaced work piece support, an opening in said .support for entry of said rotary tool into engagement with said work piece, a second jaw having surfaces for pressing work pieces into firm contact with said support closely adjacent to both of a pair of opposite edges of said opening so that said work pieces will be supported closely adjacent to both sides of said selected flat areas of said work pieces, said jaws being pivotally interconnected for pivoting between an open position for receiving, positioning, and removing work pieces and a closed position for holding and protecting work pieces, jaw holding means for holding said jaws in said closed position, manual release means for releasing said jaw holding means and bearing surfaces on said chuck for cooperating with said chuck rest to support said chuck and rigidly align saidwork piece support with the axis of rotation of said rotary tool. 1

13. In a machine for producing grooves in selecte areas of thin, flat, brittle work pieces of various sizes, thicknesses, and shapes, a rotary abrasive tool mounted in said machine for rotation about a fixed axis, motor drive means for rotating said tool, a chuck for holding selected areas of said work pieces in contact with said tool for sectioning said selected areas and a chuck rest for supporting and aligning said chuck in said machine, said chuck including a first jaw having a rigid flat surfaced work piece support, an opening in said support for entry of said rotary tool into engagement with said holding means. 

1. In a machine for sectioning thin flat solid materials, a rotary abrasive tool mounted in said machine for rotation about a fixed axis, motor drive means for rotating said tool, a chuck for adjustably positioning and holding thin flat work pieces in contact with said tool for sectioning selected flat areas of said work pieces and a chuck rest for supporting and aligning said chuck in said machine, said chuck including a first jaw having a rigid flat surfaced work piece support, an opening in said support for entry of said rotary tool into engagement with said work piece, a second jaw having surfaces for pressing work pieces into contact with said support closely adjacent to both of a pair of opposite edges of said openings so that said work pieces will be supported closely adjacent to both sides of said selected flat areas of said work pieces, said jaws being pivotally interconnected for pivoting between an open position for receiving, positioning, and removing work pieces and a closed position for holding and protecting work pieces, jaw holding means for holding said jaws in said closed position, manual release means for releasing said jaw holding means and bearing surfaces on said chuck for cooperating with said chuck rest to support said chuck and rigidly align said work piece support with the axis of rotation of said rotary tool.
 2. A machine in accordance with claim 1, in which said chuck rest comprises a shaft mounted in said machine with the axis of said shaft parallel with the axis of said rotary tool and in which said bearing surfaces comprise a pair of V shaped notches spaced apart in the lower end of said chuck.
 3. A machine in accordance with claim 1, in which said jaw holding means comprises a mechanical latch and a latch keeper and in which all parts of said latch and said latch keeper are recessed into the jaws of said chuck.
 4. A machine in accordance with claim 1 in which said second jaw includes resilient material located closely adjacent to said pair of opposite edges when said jaws are closed (for pressing work pieces into firm contact with said support) so that said work pieces will be pressed into contact with said support only in areas closely adjacent to said edges of said opening.
 5. A machine in accordance with claim 1 in which said first jaw is channel shaped in cross section and includes an interior surface and an external surfAce (an elongated opening passing) and in which said opening is elongated and passes from said interior surface to said exterior surface, with the longitudinal center line of said opening parallel with the axis of rotation of said rotary tool and in which said exterior surface is concave in cross section adjacent to the longitudinal sides of said opening to permit part of said rotary tool to protrude through said opening to perform a sectioning operation on a work piece held in said chuck.
 6. A machine in accordance with claim 5, in which said interior surface is embossed along the longitudinal edges of said opening so that flat work pieces will be contacted closely adjacent to said opening even when said work pieces have slightly irregular surfaces or when particles of material are present on other areas of said interior surface.
 7. A machine in accordance with claim 4, in which at least that part of said resilient material which contacts said work pieces is resistant to wetting and non adhesive to metals and in which said work piece support is easily wettable so that the presence of moisture between said work pieces and said work piece support will retain said work pieces in position on said support when said jaws are in said open position and when said jaws are moved from said closed position to said open position.
 8. A machine in accordance with claim 1, in which at least two of said bearing surfaces are adjustable by means of set screws mounted in said first jaw.
 9. A machine in accordance with claim 1, in which at least part of said second jaw is translucent.
 10. A machine in accordance with claim 1, in which at least part of said first jaw is channel shaped in cross section and said second jaw lies within said part of said first jaw when said jaws are in said closed position.
 11. In a machine for sectioning thin flat easily frangible solid materials such as germanium arsenide or silicon as used for substrates in the semi-conductor industry, a rotary abrasive tool mounted in said machine for rotation about a fixed axis, motor drive means for rotating said tool, a chuck for holding selected areas of said work pieces in contact with said tool and a chuck rest for supporting and aligning said chuck in said machine, said chuck including a pair of hinged jaws having an open position for receiving, positioning, and removing work pieces and a closed position for holding and protecting work pieces, said work pieces being substantially completely covered on both sides by said jaws except for said selected areas of said work pieces when said jaws are in said closed position.
 12. In a machine for producing grooves which have precisely known and uniform section radius to enable the measurement of thickness of thin layers of solid materials by a procedure which includes optical measurement of the groove width at the top and at the bottom of each layer to be measured, a rotary abrasive tool mounted in said machine for rotation about a fixed axis, motor drive means for rotating said tool, a chuck for holding selected areas of work pieces in contact with said tool for sectioning said selected areas and a chuck rest for supporting and aligning said chuck in said machine, said chuck including a first jaw having a rigid flat surfaced work piece support, an opening in said support for entry of said rotary tool into engagement with said work piece, a second jaw having surfaces for pressing work pieces into firm contact with said support closely adjacent to both of a pair of opposite edges of said opening so that said work pieces will be supported closely adjacent to both sides of said selected flat areas of said work pieces, said jaws being pivotally interconnected for pivoting between an open position for receiving, positioning, and removing work pieces and a closed position for holding and protecting work pieces, jaw holding means for holding said jaws in said closed position, manual release means for releasing said jaw holding means and bearing surfaces on said chuck for cooperatIng with said chuck rest to support said chuck and rigidly align said work piece support with the axis of rotation of said rotary tool.
 13. In a machine for producing grooves in selected areas of thin, flat, brittle work pieces of various sizes, thicknesses, and shapes, a rotary abrasive tool mounted in said machine for rotation about a fixed axis, motor drive means for rotating said tool, a chuck for holding selected areas of said work pieces in contact with said tool for sectioning said selected areas and a chuck rest for supporting and aligning said chuck in said machine, said chuck including a first jaw having a rigid flat surfaced work piece support, an opening in said support for entry of said rotary tool into engagement with said selected areas of said work pieces, a second jaw for pressing work pieces into firm engagement with said support, said jaws being pivotally interconnected for pivoting between an open position for receiving, positioning, and removing said work pieces and a closed position for holding and protecting said work pieces, resilient material mounted in said second jaw closely adjacent to each of a pair of opposite edges of said opening when said jaws are in said closed position, jaw holding means for holding said jaws in said closed position, and manual release means for releasing said jaw holding means. 